The optical link is relative directional and can be improved by placing the leds in different angles and placing reflectors behind them. The optimal input audio level is 100 – 200mV for 1.2 – 2.4 m ...

This Infrared transmitter can activate IR based switching circuits from a distance of 10 meters or more. It is a high power IR transmitter driving two IR LEDs through a Darlington transistor BD 139 to ...